Question: Simplify the following expression: $k = \dfrac{20rt + 5t}{5st + 15rt} + \dfrac{25t^2 - 10rt}{5st + 15rt}$ You can assume $r,s,t \neq 0$.
Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{20rt + 5t + 25t^2 - 10rt}{5st + 15rt}$ $k = \dfrac{10rt + 5t + 25t^2}{5st + 15rt}$ The numerator and denominator have a common factor of $5t$, so we can simplify $k = \dfrac{2r + 1 + 5t}{s + 3r}$